The findings were part of his biological passport. Such passports, unlike traditional drug tests, track athletes' blood data for signs of doping over a long period. A single suspicious passport sample on its own isn't considered grounds for a ban and doesn't mean any trace of a banned substance was found.

The data posted by the Fancy Bears group include alleged IAAF correspondence from April 2016 that lists Farah among athletes whose blood data was considered suspicious.

Farah's profile is flagged as "likely doping" in one document attached to the April 2016 email, allegedly following analysis by an unidentified expert. Another file attached to the same email says the British runner's profile is "now flagged as 'normal' with the last sample." It isn't clear exactly why there was any change or exactly what evidence may have been behind any suspicion.

"Any suggestion of misconduct is entirely false and seriously misleading. Mo Farah has been subject to many blood tests during his career and has never failed a single one," according to an email from a public relations firm representing Farah.

"We have never been informed of any of Mo's test results being outside of the legal parameters set by the relevant authorities, nor has Mo ever been contacted by the IAAF about any individual result. It is totally incorrect and defamatory to suggest otherwise."

The data appeared to be genuine and hacked from the IAAF in April, according to the track body, which apologized later Thursday to athletes whose confidentiality had been breached.

"The IAAF offers its sincerest apologies to the athletes who believed their personal and medical information was secure with us," the Monaco-based body said.

IAAF President Sebastian Coe acknowledged that security needed to be reviewed, though urged against casting suspicion on athletes named in the hack.

"It would be wrong to make assumptions based upon leaked documents without the full evidence and that evidence being put in context," Coe said.

The U.S. Anti-Doping Agency is investigating Farah's coach, Alberto Salazar. He has been accused of skirting anti-doping rules while training some of his athletes at the Nike Oregon Project, a high-profile group that promotes distance running.

The 2013 world race-walk champion Robert Heffernan of Ireland also appears in the documents with the note: "Profile Suspicious flagged 'Normal' since the very recent sample." Heffernan's agent, Denny McVeigh, told The Associated Press that Heffernan had been investigated because of a blood sample he had given shortly after surgery on a hernia. The effects of the operation, and a related dose of an anti-blood clotting agent, caused Heffernan's blood to appear abnormal, McVeigh said.

The IAAF said the data — including numerous emails purportedly written by top IAAF managers — was apparently obtained in a hack the organization reported in April.

At least four athletes whose biological passports were listed as suspicious have received doping bans for offenses unrelated to the passport data. Some were already banned at the time the email containing the data was apparently sent.

Assessing biological passport data is "a dynamic process in which the status of an athlete's profile can change at any time," the IAAF said Thursday.

Almost all the athletes named in the documents are from endurance events, where biological passports are particularly good at identifying the effects of drugs that boost the blood's ability to transport oxygen. But one prominent athlete from a throwing event also is listed as "likely doping."

The Associated Press has not been able to verify whether the documents are accurate.

Fancy Bears, known under a variety of other names, has been tied to the Kremlin by U.S. and German intelligence, as well as private researchers.

The group has previously mixed fake data with genuine records, the World Anti-Doping Agency said after it became the victim of a hack last year. WADA has said the hackers come from Russia, contending the hacks are "retaliation" for investigations into Russian drug use, which led to sanctions on Russia from WADA and the IAAF.